How to bypass the 4wabs module for troubleshooting

53988 Views 71 Replies 18 Participants Last post by 8vettes, 6 mo ago

Turbo Ghost

Discussion Starter · Feb 10, 2009 (Edited by Moderator)

Moderators, if you feel this post is appropriate, would you mind making it a "sticky" or whatever it is referred to here? Thank you!

If you happen to suddenly lose your speedometer/odometer/cruise-control and your automatic transmission starts shifting roughly, This will let you know if your 4wabs module is the cause of your problem by bypassing it and seeing if everything else works after.

The module is located directly behind the driver's side headlight and uses a 10mm bolt to hold the connector in place. Loosen the bolt (it doesn't come out, just loosens) and pull the connector from the module. Then jump the pins as shown in the pic and place the connector in a safe position so the jumpers won't get knocked loose while driving. Make sure the connections are good and clean and the jumpers are firmly in place. Contact cleaner will help. Then, drive the vehicle a short distance and you should immediately regain your speedometer/etc. If you do not, then your problem is NOT the module and you can begin searching elsewhere for the problem. Good searchwords are 4wabs, psom, vss, I hope this helps!

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Steve83

· #2 · Feb 10, 2009

We have a forum for Technical Writeups, so maybe a mod/admin will move this there.

...or maybe it should just be combined with the original thread. :shrug

http://fullsizebronco.com/forum/showthread.php?t=138574

bronco4life101

· #3 · Jul 2, 2010

well i tried the jumpers,it made my speedo worse.so i guess it ist the abs. i hope its the psom cause i ordered one too day.

miesk5

· #4 · Jul 3, 2010

yo,
hope so! but as I mentioned in your other post about PSOM;
there could be other factors causing the PSOM needle to jump; such as;
a damaged ABS tone ring/or shavings in the rear differential
a bad ABS (also called VSS) Sensor or it's connector/wiring (corroded connections/conductors)
other connectors along da path thru the 4WABS Control Module & then up to da PSOM (Speedo/odometer) and then to the EEC/Cruise Control/ Overhead Console
& of course a faulty PSOM; sometimes due to a loose or bad solder joint inside

GL!

My ABS Module was fried and caused the PSOM needle to jump wildly, tranny to downshift suddenly and AMBER ABS light to turn on; also had a DTC and check engine light

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sonoraspray

· #5 · Jan 12, 2011

speedometer problem

:doh0715:i was habin alot of trouble with my 1995 ford brnco but i did the 4wabs module bypass and my bronco was like a dream tanks alot guys:beer

Turbo Ghost

Discussion Starter · #6 · Jan 13, 2011

Odd? I received an email showing another post had been made but, I don't see it here? The last post I see is from 7/3/2010. Is it my browser messing-up again or did the post just disappear?

Turbo Ghost

Discussion Starter · #7 · Mar 19, 2012

Well, a few years after the original post, my jumpers are still going strong. The only issue I've had is my cruise control has never worked since but, everything else is fine.

Steve83

· #8 · Mar 19, 2012

If the speedo works, then this mod has nothing to do with the cruise.

Turbo Ghost

Discussion Starter · #9 · Mar 19, 2012

Any theories on what it might be? It worked fine until the module went bad and hasn't worked since.

catsnw

· #10 · Mar 20, 2012

If your 94 is like my 95 there is no direct connection. See above picture^^^

You just got (un)lucky. Check the servo connector for corrosion or burnt pins if you didn't get the recall harness. Which is actually why my cruise doesn't work. The harness is there but the connector got burnt up.

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Turbo Ghost

Discussion Starter · #11 · Mar 20, 2012

Hey! Thanks for the info! I didn't know about a recall. I wonder what the odds are of me getting a new harness? I've got friends at the local dealership. I'll have to check with them to see what I can get done! It would be so great to have cruise back. I'll be glad when I can get enough money together to get a new ABS module! The jumpers work great but, I'd still rather have things the way their supposed to be!

Turbo Ghost

Discussion Starter · #12 · Mar 20, 2012

Hmm? I notice a connection (if I'm reading it right) between the compass/temp gauge and the servo. My Temp takes about 10 minutes after you start the vehicle before it comes on!?

catsnw

· #13 · Mar 20, 2012

About the recall. Unplug the brake sensor on the mc before your truck burns down!

That connection is only to calculate in the windchill because of vehicle speed iirc.

If you need the recall harness I have a spare (pm we can work out details) or you can jy it usually.

And if you need more diagrams from that book I can scan them for you. I accutally used this mod when my abs when out so I feel as I should repay the favor.

Steve83

· #14 · Mar 20, 2012

Turbo Ghost said:
I didn't know about a recall.

Where have you been - it's one of the largest in history.

opc1: This is probably the ~10th revision, and they've done probably 10 more since. If your truck is registered to your home address, you should have gotten at least 3 notices.

Turbo Ghost said:
My Temp takes about 10 minutes after you start the vehicle before it comes on!?

Again - that's an unrelated coincidence. The early OHC modules are notoriously unreliable, but they're easy to swap out. Read the captions in my OHC & Dual Visors album.

catsnw said:
That connection is only to calculate in the windchill because of vehicle speed iirc.

It prevents the display from showing erroneous data due to engine heat.

catsnw said:
If you need the recall harness I have a spare (pm we can work out details) or you can jy it usually.

They're free at the dealership, including installation, and it's necessary for them to do the work so he (or any subsequent owner) doesn't get future notices.

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Turbo Ghost

Discussion Starter · #15 · Mar 20, 2012

Ah! I've had the recall harness that connects to the master cylinder done. I thought this was something else. I had it done to my Bronco and F-150Nite. I'll have to take a look at it. IIRC, there was a fusible link in it? I wonder if it might have blown? If it did, would I get a fault code or anything? Since I have the ABS module bypassed, my ABS light is on all the time anyway.
I'll take a look at those links/diagrams and see what I can work out this weekend.
Thanks for all the info!!

Steve83

· #16 · Mar 20, 2012

Not a fusible link - it should have 2 blade fuses. No, the cruise system doesn't generate fault codes. Read this & the PREV/NEXT pics:

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Turbo Ghost

Discussion Starter · #17 · Mar 21, 2012

Thanks! I'll check it out and see what I can determine.

RLVBronco

· #18 · Sep 14, 2016

Termianl size?

What size terminals did you use on the jumper cables?

Deranged.dave1

· #19 · Nov 8, 2017

Cant see the pic of the jumpers on the 4waps module

Turbo Ghost said:
Well, a few years after the original post, my jumpers are still going strong. The only issue I've had is my cruise control has never worked since but, everything else is fine.

Help my 95 is doing the samw thing. Shifting hard abs and check engine light on overdrive light flashing
Need to make jumpers

miesk5

· #20 · Nov 8, 2017 (Edited)

Yo Dave,
Luckily, i saved his pic awhile ago.
4WABS Control Module CONNECTOR Bypass for PSOM Operation due to Bad 4WABS Control Module; "...jumper 14 to 21, & 39 to 22..." MIESK5 NOTE;. I did this on our 96; The 4WABS control module was toast due to 2 microprocessor failures...

"...jumper 14 (CKT 530, LG/Y)to 21 (CKT 519 (LG/BK) & 39 (CKT 491 (O/LB)to 22 (CKT 523, R/PK)..."

by Turbo Ghost

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